1. Field of the Invention
This invention relates to a compound ball bearing type pulley mainly used for office automation apparatuses.
2. Description of the Prior Art
A usual pulley used for office automation apparatuses, as shown in FIG. 2, comprises a spindle 31, a pair of conventional ball bearings 32, 32 mounted on the spindle 31 and a sleeve 33 having outer flanges 34, 35 which serve as rims of the pulley on its upper and lower end.
The conventional ball bearing 32 has an inner ring 36, an outer ring 37 and balls 38.